Erratum to The effect of dew on the use of RADARSAT-1 for crop monitoring: Choosing between ascending and descending orbits [Remote Sensing of Environment 80/2 (2002 241–247)]

Radar sensors, like RADARSAT-1, can be a valuable tool for monitoring agricultural crops. RADARSAT-1 imagery can be acquired regardless of cloud cover, and the satellite can be programmed to collect imagery in a wide range of beam modes and incidence angles. This flexibility significantly increases the revisit schedule, thereby ensuring that images can be acquired during key crop growth stages. Users also have the flexibility of choosing acquisitions during either ascending or descending orbits. However, the condition of agricultural targets can change diurnally, and consequently, care must be taken in choosing between RADARSAT-1ʹs dawn and dusk orbits. In temperate regions, early morning dew is often present on the crop canopy at the time of the satellite overpass. Consequently, this study used fine mode dawn/dusk image pairs acquired over western Canada to examine the potential effect of dew on operational crop mapping. The data consistently demonstrated that backscatter increased when dew was present on the canopy. However, overall crop separability did not appear to be affected by the presence of dew. These results indicate that although choice of orbit is less important for crop classification, the probability of dew on the canopy must be carefully considered when users are extracting quantitative crop information from radar imagery.